Unitary corona reactor including opposed planar non-vitric dielectric walls



p 7, 1968 w. R. BROWNE ETAL 3,402,119

UNITARY CORONA REACTOR INCLUDING OPPOSED PLANAR NON-VITRIC DIELECTRICWALLS Filed May 10, 1965 2 Sheets-Sheet 1 [)7 ven at 0/29. MW/m RBPO wn6, John Z No Namamz by 14m 777a)" A C t orney UNITARY coRoNA RisAcToRINCLUDING OPPOSED PLANAR NoN-vr'rRrc DIELEC- TRIC WALLS of coronareactors were constructed from glassware. In considering operationsbeyond the laboratory level, however, such reactors present seriousproblems stemming from the propensity toward breakage of glassware,includ- William R. Browne, Scotia, and John E. McNamara, 5 Safetyhazards, to Personnel g q p ent, the re- Schenectady, N.Y., assignors toGeneral Electric Comflulrfiirflent of Speclal Care handhbg and mountlng,the Daily, a corporation f N York inability of glassware to reliablywithstand over-all high Filed May 10, 1965, Ser. No. 454,627temperatures or localized elevated temperature, the risk 3 Claims. (Cl.204-312) of placing a process off-stream, etc.

. I industrial environments, mo rugged types f corona reactors have beenproposed. Such reactors typi- ABSTRACT OF THE DISCLO RE cally include ahousing forming a chamber or plenum A comma reactor is disclosed whichis formed as a to confine the gaseous media in which the corona is to besingle unitary structure by a i l molding operation propagated,electrodes mounted w1thin the housing, units f o a moldable, dielectricmaterial Such as a ceramic to mount electrodes 1n the desired relationto the housing or Synthetic resin which is chemically inert with respectand to each other, d1electr1c barriers either attached to to thereactant to be treated therein. The reaction chamthe elfictl'odbs p btbefebetWeel} y parate ber comprises inlet and outlet means with areaction zone moubtmgs, and, 111 dynamic reactors, gl s t0 dlrecttherebetween, the reaction zone being defined by a pair fiowlngreacbaflts tbfqllgb the C na. Wh11e such corona of ll l b i llrectangular ll portions haw reactors avoid the dlstadvantagesencountered In using ing smooth interior face portions spaced a constantdislaboratory glassware, Such feactofs heretbfore produced tame apart hspacing di i being much smaller have been relatively expenslve due tothen unduly comthan any lateral dimension of the rectangular wall por- Pand cumbersome structural f orms.

tion. The outer surfaces of the rectangular wall portions P 15 an l l ofour lbventloll t0 PTOVlde 511111916,

have electrode supporting portions which are substantially 2 un1ta1:yeconomlcal'ly fflbl'lcated' I HH r ac Ol'.

parallel to each other and to the corresponding inner sur- It 13 anotherto Provlde a corona r a t r of face of the rectangular wall portions.l'llgge'd I1- tI is an additional ob ect to provide a corona reactorcapable of operating at elevated temperatures with mini- Our inventionrelates to a unitary corona reactor. ma1r1 Sk of damage- When two bareelectrodes separated by a gaseous It 15 a further b l of 0111 lnvellbobp media are subjected to a potential difference, an electric Poronareflctor Wblcb can be formed y a slmple moldarc may be generated betweenthe electrodes by ionizamg opbratlontion of the gas. An electric arc isa high current, low These and b? l f 0f 9 n l n are accomvoltageelectrical phenomenon visually discernible by its 5 p b y PTOVldlIlg adlelectflc Corona reactor boublng limited areal extent and sharpboundaries. If the preshavlng first and pp Planar, substabtlany sure,and hence density, of the gaseous media lying be- Parallel W811 port1onsa fi st and e ond electrodes tween the electrodes is reduced well belowatmospheric mounted bxteflol'ly 9 581d bollslbg and adlacbnt Sald firstpressure, a potential difference applied to the electrodes and secgmd aport1ons, respectlvelywill produce a glow discharge. A glow discharge ischar- 40 our lllvelltlfm yb better. b fl y reference acterized by a softdiffused appearance extending over a t e llowlng deta led descriptionconsidered in consubstantial area and lacking distinct boundaries. Suchdis- Junctlon Wltb f dfawlngs, 111 Wh lbb charge is formed byelectrically energizing gaseous par- FIGURE 1 15 a from elevatlon, P y1n F ticles by direct contact with the electrodes. The low presa Coronafeabtbf l 1 1 sure, however, prevents the formation of a gaseous ionicFIGURE 2 15 a slde P y lIl Sectlon, of t e conducting bridge between theelectrodes which would Corona reactor b FIGURE tha are; first? of irdand com letel distinct type of electrical dis- 1 e "f ch a rg e istermed a c o rona discharge. When two electrodes FIGURE 4 18 R sldfielevatlolhfpaftly lglrj s a 0f the are separated by a gaseous media andalso by one or modlfiedform 0f corona t r FIGU more dielectric barriers,the application of an alternating Refefrlng t0 FIGURES 1 and a Cor a ractor 1 current to the electrodes will capacitively excite the gase- 15Connected Y boupllng collar 2 t0 Inlet b dl lthll ous media to produce acorona discharge therein. Such d by a upllng c01lar 4 to an outlet COI1dl1]11t 5 T 2 type discharge differs from an electric arc in being ahigh C na reactor is compr sed of a d electric1 ousing voltage, lowcurrent phenomenon. Further, corona dlsformed of an 3 fabflcated, r-vtrle 1 tlrlc Inacharge, while visually similar to glow discharge,differs terral such as, for example, a synthetic resin. The ous mgmarkedly therefrom in that corona discharge propagaincludes a first wallportion 7 which 18 of uniform thicktion does not require direct contactbetween the elecness Directly opposite and spaced from the first walltrodes and the gaseous media or reduced pressures to portion 1s asimilar substantially parallel wall portion avoid arcing. Additionally,unlike an electric are or a glow 8. Each of first and second wall portons 7 and 8 merge discharge, a corona discharge can be generated only bysmoothly into surrounding wall portions 9 and 10, rean electrical energysource of alternating current. spectively, of greater thickness than thewall portions Various forms of apparatus have been constructed 7 and 8.In the area where the wall port1ons 7 and 8 merge for treating gases andliquids in the presence of a corona into the surrounding wall port1ons 9and 10, respectively, discharge. The earliest and still most widely usedforms an arcuate surface 11 is formed on the exterior surface of thehousing. The surrounding wall portions 9 and 10 are joined together byintegrally formed side walls 12 and 13.

Mounted adjacent the wall portions 7 and 8 are electrodes 14 and 15,respectively. Electrode 14 is provided with a planar face portion 16conforming to the exterior surface of the wall portion 7 and an arcuateperimeter portion 17 conforming to the arcuate surface 11. Electrode issimilarly provided with a planar face portion 18 and an arcuateperimeter portion 19. The electrode may be formed as separate metallicelements pressed against or adhered to the housing or may be formed as aconductive coating on the exterior of the housing such as a conductivepaint, electrodeposited metal, etc.

It is noted that the electrode 14 and the wall portions 7 and 9cooperate to form an electrode assembly including an electrode anddielectric barrier. The electrode 15 and the wall portions 8 and 10cooperate to form a similar electrode assembly. The sidewalls 12 and 13act as means for joining electrode assemblies in spaced relation throughthe dielectric barriers.

The wall portions 9 and 10 and side walls 12 and 13 converge at each endof the housing to form inlet and outlet necks 20 and 21. The spacebetween the walls 12 and 13 and wall portions 7 and 8 forms a chamber 22in which a corona may be propagated. An inlet conduit 23 may beconnected to conduit 3 to introduce a material to be treated into thecorona within the chamber 22. Material is exhausted from the chamber 22through neck 21 and outlet conduit 5 connected to conduit 24. A portionof the material exhausted from the corona reactor may be recirculated bymeans of conduit 25 extending from outlet conduit 5 to inlet conduit 3and having a pump means such as 26 connected therein.

A potential is supplied to the electrodes from a source of alternatingcurrent 27. The alternating current source is connected to a tuningcircuit schematically shown at 28. The tuning circuit in its threesimplest forms may be comprised of a variable capacitance and inductancein shunt, a variable capacitance in shunt and an inductance in series,or a variable capacitance in series and an inductance in shunt. Othertuning circuits are of course known and utilizable. Electrical leads 29and 30 extend from the tuning circuit to electrodes 14 and 15,respectively.

In operation, the corona reactor 1 is supplied with a material to betreated through conduits 23 and 3. Subsequent to purging the system, anelectrical potential is applied across the electrodes 14 and 15 throughleads 29 and 30. A corona discharge is formed within the chamber 22between the electrodes and in intimate contact with the material to betreated. The arcuate perimeter portions 17 and 19 of the electrodes 14and 15 provide for a rapid decay in electric field strength beyond theedges of the electrodes thereby preventing power losses through strayedge currents not contributing to the propagation of the coronadischarge. The tuning circuit 28 provides for electrical load circuitpower factor correction so that the electrical energy source 27 secsonly the resistive load represented by the corona power.

The material undergoing treatment exhausts from the corona reactorthrough neck 21 and conduit 5. The material is subsequently transportedto the next process phase through conduit 24. If desired, a portion ofthe material treated may be recirculated through conduit 25 throughoperation of pump means 26.

FIGURES 3 and 4 illustrate a second exemplary form of corona reactor100. The reactor includes a unitary molded ceramic housing 101. Thehousing terminates at its upper extremity in a flange 102. The lower endof the housing is shown provided with a port 110.

A tapered fitting 103 is shown connected to the upper end of the coronareactor having a flange 104 at one end and a ring coupling 105 at theother end. An annular sealing ring 106 is mounted between flanges 102and 104. The flanges are pressed together to compress the sealing ringby means of clamping rings 107 and 108 joined by tie bolt assemblies109. The ring coupling connects the tapered fitting 103 to afluidconduit.

A fluid conduit 111 is shown sealed against the housing within port byan O-ring seal 112. The O-ring seal is held in position on the conduitby shoulders 113 and 114. The tapered fitting 103, outlet conduit 111,and attendant elements form no part of the corona reactor 100 but aremerely exemplary of the type of connection means which may be employedin combination with the corona reactor.

The housing 101 of the reactor includes spaced, opposed, substantiallyparallel front and rear wall portions 115 and 116 which are joined attheir edges by side wall portions 117 and 118. Electrodes 119 and 120are mounted adjacent the wall portions 115 and 116, respectively. Theelectrode 120 is connected to ground by lead 121. The electrode 119 isconnected to a tuning circuit 122 schematically shown by a lead 123. Thetuning circuit is connected to ground by lead 124 and to a source ofalternating current 125.

The corona reactor 100 may be operated similarly to the coronareactor 1. While reactor operation has been disclosed in terms ofcontinuous circulation of reactants, it is contemplated that thereactors may be used to treat fluids statically contained therein. Incertain instances, it may be desired to treat a fluid contained in adielectric package without removing the fluid from the package. Thecorona reactor 100 is particularly amenable to such use. In certaininstances, it may be desired to introduce a solid substrate into thecorona reactor to be coated by fluid undergoing corona treatment. Also,it may be desired to continuously pass a substrate through the reactorfor treatment or coating within the corona zone. In such instance, theconfiguration of the inlet and outlet openings of the housing may beformed to correspond to that of the substrate. As previously indicated,the inlet and outlet couplings of the corona reactor may be chosen froma wide variety of known coupling structures. In certain applications, itmay be desired to purge the reactor with a fluid other than the fluid tobe treated, such as helium, argon, nitrogen, etc. Provision for thecirculation of a purging fluid may be made by providing suitableconnections to the inlet and outlet conduits or by providing additionalinlet and outlet ports in the housing. While the reactor electrodes areshown mounted exterior of the housing, it is of course contemplated thatthe electrodes may be encased within the housing according to theteaching of our abandoned, previously filed application Ser. No.409,199, filed Nov. 5, 1964.

Numerous additional modifications will be readily suggested to thoseskilled in the art. For this reason, it is intended that the scope ofour invention be determined by reference to the following claims.

What we claim as new and desire to secure by Letters Patent of theUnited States is:

1. A unitary corona rector comprising a hollow housing integrally castfrom a non-vitric dielectric material which is chemically and physicallyinert with respect to the environmental conditions of the reaction, saidhousing comprising inlet means for the reactant, a reaction chamber, andoutlet means for the reaction product, said reaction chamber comprisinga pair of opposed, spaced, substantially parallel, planar wall portions,said wall portions each having opposed electrode supports formed bysubstantially rectangular recesses in their outer surfaces, each of saidrecesses being composed of a planar recessed surface having an arcuateperimeter portion curving outwardly of said planar recessed surface,said planar recessed sufaces being substantially parallel to each otherand to the inner surfaces of said planar wall portions, and electrodescomprising electrically conductive layers coating the surfaces of saidrecessed portions including said arcuate perimeter portions.

2. The corona reactor as recited in claim 1 wherein the space betweenasid wall portions defined by said References Cited oposed electrodescomprises a substantially rectangular t'o zon wherein said space has atransverse d' UNITED STATES PATENTS reac 1 n e unen- 2,327,457 8/1943Raisch 204317 slog substantially smaller than any lateral dimenslon of 52,364,940 12/1944 Bias 20 164 Sal mac Zone- 2,864,755 12/1958 Rothacker204-165 3. The corona reactor as recited 1n claim 1 wherein 3,320,1515/1967 Tepe et a1 204 176 said electrically conductive layers comprisecoatings adherently deposited on the surfaces of said recesses. ROBERTK. MIHALEK, Primary Examiner.

